Raising the temperature will speed up the parasite's life cycle, to kill the parasite you would have to raise the temperature higher than most fish can tolerate, that is a special concern with your goldfish. When you raise the temperature of your tank, also increase the oxygenation of the water. You can do so by lowering the water level if you have a waterfall-type filter, it will create a bigger splash when the water returns to the tank, creating more bubbles, or by adding an air-stone to the tank (connected to a pump and airline!)
If using medication follow the instructions on the package exactly, and never mix treatments unless it is stated so on the package!!!
If using the heat salt method, as said before, raising the temperature speeds up the life cycle. The spots will fall off the fish into the gravel. At this point doing gravel vacs daily would help remove the en-capsuled cysts from there, preventing those to become free-swimmers! Ensure to replace the right amount of salt/water mix back into the tank, and always dissolve the salt before adding it to the tank!
The remaining en-capsuled cysts hidden in the substrate then mature and the free swimmers emerge. Any fish spending a lot of time near the substrate are most susceptible to get infected, but it is during this time that the medication or salt is actually effective. The way the salt works, as I understood it, is through osmosis the water is being pulled out of the parasite's cells killing it.
With scale-less fish you can still try the salt method, but go with only half the dose of salt. With scale-less fish, doing daily gravel vacs will be advisable since it reduces the chances of re-infection greatly since you reduce the amount of possible free-swimmers!
I have no experience with gold fish, or Koi, but doing a quick google search showed people have used this method with them successfully.
Good luck getting rid of the ich, I believe most strains are taken care of in two weeks time!
